Liquid oxygenation device and liquid oxygenation method for underground coal gasification

Abstract

This invention discloses a liquid oxygenation device for underground coal gasification, comprising a liquid oxygenation section, a heat-absorbing section, and a gas-oxygen injection pipe. The liquid oxygenation section has a first chamber and a second chamber that are independent of each other. The front end of the first chamber of the liquid oxygenation section is connected to the output end of the liquid oxygen delivery pipe. The heat-absorbing section has a gas-oxygen delivery chamber and a heat-absorbing chamber that are independent of each other. The front end of the gas-oxygen delivery chamber of the heat-absorbing section is connected to the rear end of the first chamber of the liquid oxygenation section. The front end of the heat-absorbing section's heat-absorbing chamber is connected to the rear end of the second chamber of the liquid oxygenation section. The input end of the gas-oxygen injection pipe is connected to the rear end of the gas-oxygen delivery chamber of the heat-absorbing section. This invention can realize underground liquid oxygenation and stable supply in the underground coal gasification process. This invention also discloses a liquid oxygenation method for underground coal gasification.

Description

Technical Field

[0001] This invention relates to an oxygen supply device for underground coal gasification, specifically to a liquid oxygenation device for underground coal gasification. The invention also relates to a method for liquid oxygenation in underground coal gasification. Background Technology

[0002] Underground coal gasification is a highly complex and interdisciplinary technology. Thanks to the efforts of researchers both domestically and internationally, breakthroughs have been achieved in many areas of underground coal gasification technology. However, injecting sufficient oxygen into the coal seam furnace within a given time remains a challenging technical objective. Current technology involves directly supplying high-pressure oxygen-enriched gas into the underground coal gasification furnace; however, the large volume of this oxygen-enriched gas means that even with compression and transportation, the transportation efficiency per unit time remains low, severely limiting the scale and efficiency of underground coal gasification. Furthermore, the underground burner is situated in the high-temperature environment of coal seam combustion, requiring continuous circulation of cooling water both above and below ground to lower its temperature, resulting in a very complex system structure.

[0003] Chinese invention patent document CN112431582B discloses a coal underground gasification system and method capable of simultaneously transporting multiple media. By simultaneously supplying liquid oxygen and water to an underground furnace, it ensures sufficient flow of combustion-supporting gas and water vapor for precise and controllable combustion gasification of underground coal. Due to the high density, small volume, and low temperature of liquid oxygen, its transportation efficiency is higher under the same conditions, which can improve the efficiency of underground coal gasification. Simultaneously, the low-temperature liquid oxygen can also provide cooling protection for the burner. Therefore, this technology can achieve large-scale underground coal gasification, making it commercially viable. However, because the temperature of the liquid oxygen reaching the bottom of the well is too low, directly injecting it into the burning coal seam would affect combustion; therefore, the liquid oxygen needs to be oxidized.

[0004] However, existing liquid oxygen gasification units are mostly of a split structure and rely on power pumps to deliver the working fluid to provide heat for liquid oxygen gasification. Their structure and function are insufficient for underground coal gasification production. Furthermore, existing liquid oxygen gasification units are generally used on the surface, while liquid oxygen vaporizes in the confined space underground, causing rapid volume expansion and potentially resulting in detonation. Therefore, existing liquid oxygen gasification units cannot be directly applied underground. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a liquid oxygenation device for underground coal gasification, which can realize underground liquid oxygenation and stable supply in the underground coal gasification production process.

[0006] To solve the above-mentioned technical problems, the technical solution of the liquid oxygenation device for underground coal gasification according to the present invention is as follows:

[0007] It includes a liquid oxygenation section 2, a heat-absorbing section 3, and a gas-oxygen injection pipe 4. The liquid oxygenation section 2 has a first cavity I and a second cavity II that are independent of each other. The front end of the first cavity I of the liquid oxygenation section 2 is connected to the output end of the liquid oxygen delivery pipe 1. The heat-absorbing section 3 has a gas-oxygen delivery cavity and a heat-absorbing cavity that are independent of each other. The front end of the gas-oxygen delivery cavity of the heat-absorbing section 3 is connected to the rear end of the first cavity I of the liquid oxygenation section 2. The front end of the heat-absorbing cavity of the heat-absorbing section 3 is connected to the rear end of the second cavity II of the liquid oxygenation section 2. The input end of the gas-oxygen injection pipe 4 is connected to the rear end of the gas-oxygen delivery cavity of the heat-absorbing section 3.

[0008] In another embodiment, the liquefied oxygenation section 2 further has a third cavity III, the front of which is connected to the front of the second cavity II.

[0009] In another embodiment, the oxygen injection pipe 4 has multiple rings of oxygen injection holes along its length, which connect the inner cavity of the oxygen injection pipe 4 to the outside. The flow area of ​​the oxygen injection hole 41 near the output end of the oxygen injection pipe 4 is larger than the flow area of ​​the oxygen injection hole 42 near the input end of the oxygen injection pipe 4.

[0010] In another embodiment, along the conveying direction of the oxygen injection pipe 4, the flow area of ​​the oxygen injection hole increases sequentially from small to large.

[0011] In another embodiment, the liquid oxygenation section 2 includes multiple liquid oxygenation tubes 21 arranged in parallel, with gaps formed between the multiple liquid oxygenation tubes 21; the multiple liquid oxygenation tubes 21 are disposed inside a sleeve 22; the sleeve 22 is disposed inside an outer tube 23; the front part of the sleeve 22 has at least one ring of through holes 22-1; the inner cavities of the multiple liquid oxygenation tubes 21 form the first cavity I; the liquid oxygenation tubes 21 are formed between each other and between the liquid oxygenation tubes 21 and the sleeve 22; the sleeve 22 and the outer tube 23 form the third cavity III;

[0012] In another embodiment, the heat absorption section 3 of the working medium includes an oxygen delivery pipe 31, and a plurality of heat delivery pipes 32 are arranged around the oxygen delivery pipe 31; the inner cavity of the oxygen delivery pipe 31 serves as the oxygen delivery cavity; the inner cavities of the plurality of heat delivery pipes 32 constitute the heat delivery cavity.

[0013] In another embodiment, the rear end of the heat working medium conveying pipe 32 of the heat working medium absorbing section 3 is connected to the heat working medium circulation chamber VII, and the heat working medium circulation chamber VII connects the upper heat working medium conveying pipe 32 and the lower heat working medium conveying pipe 32 of the heat working medium absorbing section 3.

[0014] In another embodiment, a plurality of partitions 21-1 are spaced apart along the length of the liquid oxygen gasification tube 21; in another embodiment, adjacent partitions 21-1 are staggered; in another embodiment, the liquid oxygen gasification tube 21 is a finned tube.

[0015] In another embodiment, the area of ​​the partition 21-1 is not less than half the cross-sectional area of ​​the liquefied oxygen gasification tube 21.

[0016] In another embodiment, the first connector 5 includes a front plate 5-1 and a rear plate 5-2. The front plate 5-1 and the rear plate 5-2 are fixedly connected as a whole by a connecting pipe 5-3 to form a liquid oxygen delivery chamber IV. The first connector 5 is fixedly connected to the liquid oxygen delivery pipe 1 through the liquid oxygen delivery pipe connection hole 5-11 of the front plate 5-1, so that the liquid oxygen delivery chamber IV of the first connector 5 is connected to the inner cavity of the liquid oxygen delivery pipe 1. The first connector 5 is fixedly connected to the input end of the liquid oxygen gasification pipe 21 through the liquid oxygen gasification pipe connection hole 5-21 of the rear plate 5-2, so that the liquid oxygen delivery chamber IV of the first connector 5 is connected to the first cavity I.

[0017] In another embodiment, the second connector 6 includes a front plate 61, a middle plate 62, and a rear plate 63. The front plate 61 and the middle plate 62 are fixedly connected as one unit by a connecting pipe 64 to form a gas-oxygen gathering chamber V. The front plate 61 is connected to the output ends of multiple liquid oxygen gasification pipes 21 through multiple liquid oxygen gasification pipe connection holes 61-1. The front plate 61 of the second connector 6 connects its gas-oxygen gathering chamber V to the various components of the first cavity I. The middle plate 62 is connected to the gas-oxygen delivery pipe 31 through the gas-oxygen delivery pipe connection hole. At the input end, the middle plate 62 of the second connector 6 connects its oxygen gathering chamber V to the inner cavity of the oxygen delivery pipe 31; the rear plate 63 is fixedly sleeved on the outside of the oxygen delivery pipe 31, and the rear plate 63 is located behind the middle plate 62, forming a thermal medium transition cavity VI between the middle plate 62 and the rear plate 63; the rear plate 63 connects to the output end of multiple thermal medium delivery pipes 32 through multiple thermal medium delivery pipe connection holes 63-1, so that the inner cavity of the thermal medium delivery pipe 32 is connected to the thermal medium transition cavity VI.

[0018] In another embodiment, the third connector 7 includes a front plate 7-1 and a rear plate 7-2. The front plate 7-1 and the rear plate 7-2 are fixedly connected as one unit through a connecting pipe 7-3 to form a hot working fluid circulation chamber VII. The third connector 7 connects the hot working fluid circulation chamber VII to the inner cavity of the hot working fluid delivery pipe 32 through the front plate 7-1. The third connector 7 connects the inner cavity of the gas oxygen delivery pipe 31 to the inner cavity of the gas oxygen injection pipe 4 through the rear plate 7-2.

[0019] This invention also provides a liquid oxygenation method for underground coal gasification, the technical solution of which includes the following steps:

[0020] The first step is the vaporization of the liquid working fluid;

[0021] An external heat source provides heat to the heat absorption section 3 of the heat working medium. After absorbing heat, the liquid heat working medium at the bottom of the heat absorption section 3 vaporizes and expands to generate vapor pressure. The vapor pressure drives the gaseous heat working medium to flow upward from the lower part of the heat working medium circulation chamber VII and into the upper heat working medium conveying pipe 32. The gaseous heat working medium flows from the rear end to the front end of the heat working medium conveying pipe 32 and enters the heat working medium transition chamber VI.

[0022] The second step involves heat exchange between the working fluid and liquid oxygen.

[0023] Gaseous working fluid enters the second cavity II from the working fluid transition cavity VI and flows from back to front along the second cavity II; liquid oxygen flows from front to back in the liquid oxygen liquefaction tube 21; the gaseous working fluid outside the liquid oxygen liquefaction tube 21 exchanges heat with the liquid oxygen inside the liquid oxygen liquefaction tube 21, causing the liquid oxygen to be liquefied into gaseous oxygen and the gaseous working fluid to be liquefied into liquid working fluid.

[0024] The third step involves the reflux of the liquid heat working fluid and the ejection of gaseous oxygen.

[0025] Under its own gravity, the liquid working fluid flows from the upper part to the lower part of the second chamber II and accumulates at the bottom of the container to form hydraulic pressure. The hydraulic pressure drives the liquid working fluid to flow back from front to back to the working fluid transition chamber VI, and then flows back to the lower part of the working fluid circulation chamber VII along the lower working fluid delivery pipe 32.

[0026] Gaseous oxygen flows from the output end of the liquid oxygen gasification pipe 21 into the gas oxygen delivery pipe 31, and from the gas oxygen delivery pipe 31 into the gas oxygen injection pipe 4, and is ejected outward through the gas oxygen injection hole of the gas oxygen injection pipe 4.

[0027] In another embodiment, the gaseous working medium in the heat transfer chamber VI is divided into two paths: the first path enters the second chamber II, and the second path enters the third chamber III. The first path of working medium exchanges heat with the liquid oxygen in the liquid oxygen gasification tube 21 as it flows from back to front along the second chamber II. The second path of working medium flows from back to front along the third chamber III, flows from the front of the third chamber III into the front of the second chamber II, and exchanges heat with the liquid oxygen in the liquid oxygen gasification tube 21 at the front of the second chamber II.

[0028] The technical effects that this invention can achieve are:

[0029] This invention eliminates the need for a power pump to provide kinetic energy for transporting the working fluid. Instead, it utilizes the heat generated by burning underground coal to vaporize the working fluid, which then circulates internally within the system using vapor pressure and gravity. Therefore, the liquid oxygen vaporization process of this invention eliminates the need for a power supply system and the consumption of electrical energy, reducing related additional investment and avoiding the significant risks posed by high-temperature environments to power supply systems and precision equipment.

[0030] This invention achieves pressure and speed reduction of gaseous oxygen by setting openings of different diameters in the gaseous oxygen depressurization and deceleration delivery pipe, thereby realizing a stable supply of oxygen, improving the efficiency of oxygen use, and avoiding impact on the well wall of the combustion zone.

[0031] This invention can increase the oxygen supply in the underground coal gasification production process, thereby increasing the output of coal gasification.

[0032] The invention has a simple and compact structure, making it suitable for use in underground coal gasification production wells with limited space.

[0033] The structure of this invention is resistant to high temperatures and can meet the temperature requirements inside the well during the production process. Attached Figure Description

[0034] Those skilled in the art will understand that the following description is merely illustrative of the principles of the invention, which can be applied in various ways to achieve many different alternative implementations. These descriptions are intended only to illustrate the general principles of the teachings of the invention and are not intended to limit the inventive concept disclosed herein.

[0035] Embodiments of the invention are illustrated in conjunction with the accompanying drawings, which are incorporated in and form part of this specification, and together with the foregoing general description and the following detailed description of the drawings, serve to explain the principles of the invention.

[0036] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0037] Figure 1 This is a schematic cross-sectional view of the liquid oxygenation device for underground coal gasification according to the present invention;

[0038] Figure 2 This is a schematic diagram showing the connection between the liquid oxygen gasification section and the liquid oxygen delivery pipe of the present invention;

[0039] Figure 3 This is a cross-sectional schematic diagram of the liquid oxygenation section of the present invention;

[0040] Figure 4 This is a cross-sectional schematic diagram of the first connector of the present invention;

[0041] Figure 5 This is a cross-sectional schematic diagram of the second connector of the present invention;

[0042] Figure 6 This is a schematic diagram showing the connection between the liquid oxygen oxidation section and the heat absorption section of the working medium in this invention;

[0043] Figure 7 This is a schematic diagram showing the connection between the heat absorption section of the working fluid and the oxygen injection pipe of the present invention.

[0044] Explanation of the reference numerals in the figure:

[0045] 1 is the liquid oxygen delivery pipe, and 2 is the liquid oxygen gasification section.

[0046] 3 is the heat absorption section of the working medium, and 4 is the oxygen injection pipe.

[0047] 5 is the first connector, and 6 is the second connector.

[0048] 7 is the third connector.

[0049] 21 is the liquefied oxygen gasification tube, and 22 is the sleeve.

[0050] 21-1 is the partition of the liquefied oxygen gasification pipe, and 22-1 is the through hole of the sleeve.

[0051] 23 is the outer tube.

[0052] 31 is the oxygen transport pipe, and 32 is the heat transfer pipe.

[0053] 41 is the output oxygen injection port, and 42 is the input oxygen injection port.

[0054] 5-1 is the front panel, 5-2 is the back panel.

[0055] 5-3 is the connecting pipe.

[0056] 5-11 is the connection hole for the liquid oxygen delivery pipe, and 5-21 is the connection hole for the liquid oxygen gasification pipe.

[0057] 61 is the front plate, 62 is the middle plate.

[0058] 63 is the rear plate, 64 is the connecting pipe.

[0059] 61-1 is the connection hole for the liquefied oxygen gasification pipe, and 63-1 is the connection hole for the heat transfer fluid pipe.

[0060] 62-1 is a through hole on the outer ring, and 62-2 is a through hole on the inner ring.

[0061] 7-1 is the front panel, 7-2 is the back panel.

[0062] 7-3 is the connecting pipe.

[0063] I is the first cavity, and II is the second cavity.

[0064] III is the third chamber, and IV is the liquid oxygen delivery chamber.

[0065] V is the oxygen accumulation cavity, and VI is the heat transfer cavity.

[0066] VII is the heat circulation chamber. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains. The terms "first," "second," and similar words used herein do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Words such as "comprising" mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but does not exclude other elements or objects. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0068] like Figure 1 As shown, the present invention provides a liquid oxygen vaporization device for underground coal gasification, which is used for oxygen supply in the underground coal gasification process. It can perform controlled vaporization of liquid oxygen and provide stable oxygen supply underground.

[0069] The liquid oxygen combustion device of the present invention includes a liquid oxygen combustion section 2, a heat-absorbing section 3, and a gas oxygen injection pipe 4; the front end of the liquid oxygen combustion section 2 is fixedly connected to the output end of the liquid oxygen delivery pipe 1 through a first connector 5; the rear end of the liquid oxygen combustion section 2 is fixedly connected to the front end of the heat-absorbing section 3 through a second connector 6; and the rear end of the heat-absorbing section 3 is fixedly connected to the input end of the gas oxygen injection pipe 4 through a third connector 7.

[0070] like Figure 2 , Figure 3 As shown, the liquid oxygen gasification section 2 includes multiple liquid oxygen gasification tubes 21 arranged in parallel. The input end of the multiple liquid oxygen gasification tubes 21 is fixedly connected to the first connector 5; the output end of the multiple liquid oxygen gasification tubes 21 is fixedly connected to the second connector 6; the relative fixation between the multiple liquid oxygen gasification tubes 21 is achieved through the first connector 5 and the second connector 6; the multiple liquid oxygen gasification tubes 21 do not contact each other, so that a gap is formed between the multiple liquid oxygen gasification tubes 21.

[0071] Multiple liquid oxygen gasification tubes 21 are disposed inside the sleeve 22; a second cavity II is formed between the outer walls of the liquid oxygen gasification tubes 21 and between the outer wall of the liquid oxygen gasification tubes 21 and the inner wall of the sleeve 22.

[0072] The sleeve 22 is disposed inside the outer tube 23; a third cavity III is formed between the outer wall of the sleeve 22 and the inner wall of the outer tube 23;

[0073] The front part of the sleeve 22 is provided with at least one through hole 22-1 so that the front part of the third cavity III is connected to the front part of the second cavity II.

[0074] Preferably, a plurality of partitions 21-1 are provided at intervals along the length of the liquid oxygen gasification tube 21, and the partitions 21-1 extend from the inner wall of the liquid oxygen gasification tube 21 toward the center.

[0075] Specifically, adjacent partitions 21-1 are staggered;

[0076] Specifically, the area of ​​the baffle 21-1 is not less than half the cross-sectional area of ​​the liquid oxygen gasification pipe 21, so that the flow area of ​​the cross section where the baffle 21-1 is located does not exceed half the flow area of ​​the liquid oxygen gasification pipe 21, so that the fluid cannot flow straight in the liquid oxygen gasification pipe 21, but must follow an S-shaped path, thereby effectively extending the flow path of the fluid.

[0077] Preferably, the partition 21-1 is a crescent-shaped partition.

[0078] Preferably, the liquefied oxygen gasification tube 21 is a finned tube.

[0079] The present invention provides a plurality of baffles 21-1 inside the liquid oxygen vaporization tube 21. The baffles 21-1 can reduce the flow rate of liquid oxygen in the tube and increase the heat exchange area, thereby improving the heat exchange efficiency and facilitating the vaporization of liquid oxygen.

[0080] The staggered arrangement of the baffles 21-1 in this invention can extend the travel distance of the fluid in the liquid oxygen vaporization tube 21, thereby extending the residence time of the fluid in the liquid oxygen vaporization tube 21. This allows the liquid oxygen to have a sufficiently long time to exchange heat with the heat working medium outside the liquid oxygen vaporization tube 21, which is further beneficial to the vaporization of liquid oxygen.

[0081] like Figure 4 As shown, the first connector 5 includes a front plate 5-1 and a rear plate 5-2. The front plate 5-1 and the rear plate 5-2 are fixedly connected as one unit by a connecting pipe 5-3, forming a liquid oxygen delivery chamber IV.

[0082] A liquid oxygen delivery pipe connection hole 5-11 is provided on the front plate 5-1; the liquid oxygen delivery pipe connection hole 5-11 is matched with the liquid oxygen delivery pipe 1, and the first connector 5 is fixedly connected to the liquid oxygen delivery pipe 1 through the liquid oxygen delivery pipe connection hole 5-11 of the front plate 5-1; the liquid oxygen delivery chamber IV of the first connector 5 is connected to the inner cavity of each liquid oxygen gasification pipe 21, so that liquid oxygen can enter each liquid oxygen gasification pipe 21 through the liquid oxygen delivery pipe 1 and the liquid oxygen delivery chamber IV of the first connector 5; the inner cavity of each liquid oxygen gasification pipe 21 forms the first cavity I;

[0083] The rear plate 5-2 has multiple liquid oxygen gasification tube connection holes 5-21; the liquid oxygen gasification tube connection holes 5-21 cooperate with the liquid oxygen gasification tube 21, and the first connector 5 is fixedly connected to the input end of the liquid oxygen gasification tube 21 through the liquid oxygen gasification tube connection holes 5-21 of the rear plate 5-2.

[0084] Preferably, the flow area (i.e., the cross-sectional area inside the pipe) of the liquid oxygen delivery pipe 1 is not greater than the flow area of ​​the first cavity I (i.e., the sum of the cross-sectional areas inside each liquid oxygen gasification pipe 21).

[0085] like Figure 5 As shown, the second connector 6 includes a front plate 61, a middle plate 62, and a rear plate 63. The front plate 61 and the middle plate 62 are fixedly connected as one unit by a connecting pipe 64, forming an oxygen-gas accumulation chamber V.

[0086] The front plate 61 has multiple liquid oxygen gasification tube connection holes 61-1 for connecting the output ends (rear ends) of multiple liquid oxygen gasification tubes 21; the front plate 61 of the second connector 6 connects its gas oxygen gathering chamber V with each component of the first cavity I (i.e., the inner cavity of each liquid oxygen gasification tube 21).

[0087] The middle plate 62 has a gas oxygen delivery pipe connection hole. The middle plate 62 is connected to the input end of the gas oxygen delivery pipe 31 through the gas oxygen delivery pipe connection hole. The middle plate 62 of the second connector 6 connects its gas oxygen gathering cavity V with the inner cavity of the gas oxygen delivery pipe 31.

[0088] A rear plate 63 is fixedly sleeved on the outside of the oxygen delivery pipe 31. The rear plate 63 is located behind the middle plate 62, and a heat transfer cavity VI is formed between the middle plate 62 and the rear plate 63.

[0089] Multiple heat transfer pipe connection holes 63-1 are provided on the rear plate 63.

[0090] like Figure 6 As shown, the heat absorption section 3 of the heat working medium includes an oxygen delivery pipe 31, and multiple heat working medium delivery pipes 32 are arranged around the oxygen delivery pipe 31.

[0091] The output ends (front ends) of multiple heat transfer pipes 32 are fixedly connected to the heat transfer pipe connection holes 63-1 of the rear plate 63 of the second connector 6, so that the inner cavity of the heat transfer pipe 32 is connected to the heat transfer transition cavity VI.

[0092] The rear end of the sleeve 22 is connected to the middle plate 62; the rear end of the outer tube 23 is connected to the rear plate 63.

[0093] The middle plate 62 has an outer ring through hole 62-1 and an inner ring through hole 62-2;

[0094] The outer ring through hole 62-1 is located on the outside of the sleeve 22. The outer ring through hole 62-1 connects the rear end of the third cavity III with the heat transfer cavity VI, so that the heat transfer medium in the heat transfer cavity VI can enter the third cavity III.

[0095] The inner ring through hole 62-2 is located inside the sleeve 22. The inner ring through hole 62-2 connects the rear end of the second cavity II with the heat transfer cavity VI, so that the heat transfer medium in the heat transfer cavity VI can enter the second cavity II.

[0096] like Figure 7 As shown, the third connector 7 includes a front plate 7-1 and a rear plate 7-2. The front plate 7-1 and the rear plate 7-2 are fixedly connected as one unit by a connecting pipe 7-3, forming a heat working fluid circulation chamber VII.

[0097] The front plate 7-1 of the third connector 7 has a gas oxygen delivery pipe through hole and multiple heat working fluid delivery pipe connection holes. The front plate 7-1 of the third connector 7 connects the input end (rear end) of multiple heat working fluid delivery pipes 32 through the multiple heat working fluid delivery pipe connection holes. The front plate 7-1 of the third connector 7 connects its heat working fluid circulation chamber VII to the inner cavity of the heat working fluid delivery pipe 32.

[0098] The rear plate 7-2 of the third connector 7 has an oxygen delivery pipe connection hole. The oxygen delivery pipe 31 passes through the oxygen delivery pipe through hole of the front plate 7-1. The rear plate 7-2 of the third connector 7 is connected to the output end of the oxygen delivery pipe 31 through the oxygen delivery pipe connection hole.

[0099] The rear plate 7-2 of the third connector 7 is connected to the input end of the oxygen injection pipe 4, and the rear plate 7-2 of the third connector 7 connects the inner cavity of the oxygen delivery pipe 31 with the inner cavity of the oxygen injection pipe 4.

[0100] like Figure 1 As shown, the wall of the oxygen injection pipe 4 has multiple rings of oxygen injection holes along its length.

[0101] Each ring of oxygen injection holes includes multiple through holes evenly distributed circumferentially.

[0102] Among them, the diameter of the oxygen injection hole 41 near the output end of the oxygen injection pipe 4 is larger than the diameter of the oxygen injection hole 42 near the input end of the oxygen injection pipe 4.

[0103] Because liquid oxygen expands rapidly after gasification, it generates a very high-speed airflow at the outlet. This high-speed airflow passes through the coal combustion gasification zone in a very short time, reducing oxygen utilization efficiency and causing some impact on the well wall. This invention provides openings in the gas-oxygen injection pipe 4, with the opening diameter increasing sequentially from small to large along the fluid flow direction. Since the exhaust velocity of the small opening at the front end is high, but the exhaust volume is small, according to the kinetic energy formula, its impact on the combustion zone is relatively small. While the opening diameter at the rear end is larger, because some gas-oxygen has already been discharged from the small opening at the front end, and due to the increase in the total cross-sectional area of ​​the exhaust holes, the exhaust velocity has decreased to a lower level, thus also reducing the impact on the combustion zone.

[0104] The present invention provides a liquid oxygenation method for underground coal gasification, comprising the following steps:

[0105] The first step is the vaporization of the liquid working fluid;

[0106] An external heat source (such as burning underground coal) provides heat to the heat-absorbing section 3 of the working medium. The liquid working medium at the bottom of the heat-absorbing section 3 absorbs heat and then vaporizes and expands to generate vapor pressure. The vapor pressure drives the gaseous working medium to flow upward from the lower part of the heat-absorbing medium circulation chamber VII and flow towards the low-temperature and low-pressure liquid oxygen section, flowing into the upper heat-absorbing medium conveying pipe 32. The gaseous working medium flows from the rear end to the front end of the heat-absorbing medium conveying pipe 32 and enters the heat-absorbing medium transition chamber VI.

[0107] The external heat source required for the liquid oxygen gasification process of this invention can utilize the heat generated by the combustion of coal during underground coal gasification, eliminating the need for a dedicated heat source and thus realizing the recovery and utilization of heat from underground coal gasification.

[0108] Specifically, gaseous oxygen is first fed into the liquid oxygen delivery pipe 1, and then flows through the liquid oxygen gasification section 2 and the heat absorption section 3 in sequence, and finally flows out from the gas oxygen injection pipe 4. The coal outside the heat absorption section 3 generates combustion heat with the help of the input gaseous oxygen, which serves as an external heat source.

[0109] The second step involves heat exchange between the working fluid and liquid oxygen. Due to the temperature difference, the gaseous working fluid exchanges heat with the liquid oxygen in the liquid oxygen oxidation section 2, causing the working fluid to liquefy and the liquid oxygen to oxidize.

[0110] Specifically, the gaseous working medium in the heat transfer cavity VI is divided into two paths. The first path of the working medium enters the second cavity II through the inner ring through hole 62-2, and the second path of the working medium enters the third cavity III through the outer ring through hole 62-1.

[0111] The first heat working medium flows forward along the second cavity II; during the process of the first heat working medium flowing forward along the second cavity II, the gaseous heat working medium can exchange heat with the liquid oxygen gasification tube 21 in the second cavity II.

[0112] At the same time, the second heat working medium flows forward along the third cavity III; when the second heat working medium flows to the front of the third cavity III, it flows through the through hole 22-1 at the front of the sleeve 22 into the front of the second cavity II and exchanges heat with the liquid oxygen gasification tube 21 in the second cavity II.

[0113] Liquid oxygen flows into the liquid oxygen delivery pipe 1 through the pipeline, and then flows into the inner cavity of each liquid oxygen gasification pipe 21 through the liquid oxygen delivery chamber IV of the first connector 5.

[0114] During the process of liquid oxygen flowing from the inlet to the outlet of liquid oxygen vaporization tube 21, the liquid oxygen inside liquid oxygen vaporization tube 21 exchanges heat with the gaseous heat working medium outside liquid oxygen vaporization tube 21. When the liquid oxygen reaches the outlet of liquid oxygen vaporization tube 21, it has been vaporized into gaseous oxygen.

[0115] During the heat exchange between the gaseous working fluid in the second cavity II and the liquid oxygen in the liquid oxygenation section 2 and the liquid oxygenation tube 21, the temperature of the gaseous working fluid gradually decreases until it condenses into a liquid working fluid.

[0116] The third step involves the reflux of the liquid heat working fluid and the ejection of gaseous oxygen.

[0117] The liquid heat working fluid flows from the upper part to the lower part of the second cavity II under its own gravity, and flows into the third cavity III through the through hole 22-1 at the front of the sleeve 22, and accumulates at the bottom of the container to form hydraulic pressure;

[0118] Hydraulic pressure drives the liquid working fluid to flow from the front end to the rear end in the lower part of the second chamber II and the third chamber III of the liquid oxygenation section 2. It enters the lower part of the working fluid transition chamber VI through the outer ring through hole 62-1 and the inner ring through hole 62-2, and flows back to the lower part of the working fluid circulation chamber VII of the working fluid absorption section 3 through the lower working fluid delivery pipe 32. At the same time, the external heat source continuously supplies heat, and the liquid working fluid in the lower part of the working fluid circulation chamber VII continuously vaporizes, and the hydraulic pressure drops. Therefore, the subsequent liquid working fluid will continuously flow back to the working fluid absorption section 3, thereby realizing the dynamic internal circulation of the working fluid.

[0119] Gaseous oxygen flows from the output end of the liquid oxygen gasification pipe 21 through the gas oxygen accumulation chamber V into the inner cavity of the gas oxygen delivery pipe 31, and then flows from the output end of the gas oxygen delivery pipe 31 into the gas oxygen injection pipe 4. As the gas oxygen flows from the input end to the output end along the gas oxygen injection pipe 4, it passes through the gas oxygen injection hole and is ejected outward. Its pressure and flow rate continuously decrease (the gas oxygen flowing out from the end of the gas oxygen injection pipe 4 has a flow rate of about 20 m / s and a pressure of less than 1 MPa, which can usually reach 0.05 MPa or even lower), thus obtaining a stable oxygen flow that can be used for oxygen supply in underground coal gasification processes.

[0120] During the vaporization process of liquid oxygen in the liquid oxygen vaporization pipe 21, the pressure inside the container will increase rapidly, forming a high-speed gas that is ejected to the outlet. The gas oxygen injection pipe 4 of the present invention has gas oxygen injection holes 41 with diameters increasing sequentially from small to large along the conveying direction, which can realize the step-by-step release of oxygen, thereby making the oxygen flow out smoothly and allowing the oxygen to participate in the coal gasification reaction process smoothly.

[0121] The heat transfer medium of this invention can be steam, liquid ammonia, CO2, R134a, etc.

[0122] To allow sufficient time for liquid oxygen to vaporize, it is desirable for the liquid oxygen vaporization tube 21 to be as long as possible, so that the first heat transfer medium has enough time to exchange heat with the liquid oxygen vaporization tube 21 as it flows forward along the second cavity II. However, a longer liquid oxygen vaporization tube 21 presents a problem: the first heat transfer medium has difficulty reaching the front section of the tube, and it condenses and settles earlier after contacting the liquid oxygen, starting to flow back. This results in uneven heat exchange between the front and rear sections of the tube 21, failing to fully utilize the heat energy carried by the heat transfer medium in one cycle. Therefore, this invention provides a second heat transfer medium that can directly reach the front of the second cavity II. The second heat transfer medium experiences minimal heat loss during its forward flow, thus still possessing sufficient heat energy upon reaching the front of the second cavity II. The second heat transfer medium exchanges heat with the front section of the liquid oxygen vaporization tube 21, thereby achieving uniform heat exchange between the front and rear sections of the tube 21.

[0123] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A liquid oxygenation device for underground coal gasification, characterized in that, include: The liquid oxygen gasification section (2) has a first cavity (I) and a second cavity (II) that are independent of each other; the front end of the first cavity (I) of the liquid oxygen gasification section (2) is connected to the output end of the liquid oxygen delivery pipe (1); The heat-absorbing section (3) has an independent gas-oxygen transport chamber and a heat-absorbing section; the front end of the gas-oxygen transport chamber of the heat-absorbing section (3) is connected to the rear end of the first chamber (I) of the liquid oxygen gasification section (2); the front end of the heat-absorbing section (3) is connected to the rear end of the second chamber (II) of the liquid oxygen gasification section (2); and The oxygen injection pipe (4) has its input end connected to the rear end of the oxygen delivery chamber of the heat absorption section (3) of the heat working medium; The liquid oxygenation section (2) also has a third cavity (III), the front of which is connected to the front of the second cavity (II); The liquid oxygenation section (2) includes multiple liquid oxygenation tubes (21) arranged in parallel, with gaps formed between the multiple liquid oxygenation tubes (21); the multiple liquid oxygenation tubes (21) are disposed inside a sleeve (22); the sleeve (22) is disposed inside an outer tube (23); at least one through hole (22-1) is opened at the front of the sleeve (22); the inner cavities of the multiple liquid oxygenation tubes (21) form the first cavity (I); the liquid oxygenation tubes (21) form the second cavity (II) between each other and between the liquid oxygenation tubes (21) and the sleeve (22); the sleeve (22) and the outer tube (23) form the third cavity (III). The rear end of the heat transfer pipe (32) of the heat absorption section (3) is connected to the heat circulation chamber (VII), and the heat circulation chamber (VII) connects the upper heat transfer pipe (32) of the heat absorption section (3) with the lower heat transfer pipe (32).

2. The liquid oxygenation device for underground coal gasification according to claim 1, characterized in that, The oxygen injection pipe (4) has multiple rings of oxygen injection holes along its length, which connect the inner cavity of the oxygen injection pipe (4) to the outside. The flow area of ​​the oxygen injection hole (41) near the output end of the oxygen injection pipe (4) is greater than the flow area of ​​the oxygen injection hole (42) near the input end of the oxygen injection pipe (4).

3. The liquid oxygenation device for underground coal gasification according to claim 2, characterized in that, Along the conveying direction of the oxygen injection pipe (4), the flow area of ​​the oxygen injection hole increases sequentially from small to large.

4. The liquid oxygenation device for underground coal gasification according to claim 1, characterized in that, The heat absorption section (3) of the heat working medium includes a gas-oxygen transport pipe (31), and multiple heat working medium transport pipes (32) are arranged around the gas-oxygen transport pipe (31); the inner cavity of the gas-oxygen transport pipe (31) serves as the gas-oxygen transport cavity; the inner cavities of the multiple heat working medium transport pipes (32) constitute the heat working medium transport cavity.

5. The liquid oxygenation device for underground coal gasification according to claim 1, characterized in that, The liquid oxygen gasification tube (21) is provided with a number of partitions (21-1) spaced apart along its length; and / or, adjacent partitions (21-1) are staggered; and / or, the liquid oxygen gasification tube (21) is a finned tube.

6. The liquid oxygenation device for underground coal gasification according to claim 5, characterized in that, The area of ​​the partition (21-1) is not less than half the cross-sectional area of ​​the liquefied oxygen gasification tube (21).

7. A method for liquid oxygenation in underground coal gasification using the liquid oxygenation device according to any one of claims 1 to 6, characterized in that, Includes the following steps: The first step is the vaporization of the liquid working fluid; An external heat source provides heat to the heat-absorbing section (3). The liquid heat-absorbing material at the bottom of the heat-absorbing section (3) absorbs heat and then vaporizes and expands to generate vapor pressure. The vapor pressure drives the gaseous heat-absorbing material to flow upward from the lower part of the heat-absorbing material circulation chamber (VII) and into the upper heat-absorbing material conveying pipe (32). The gaseous heat-absorbing material flows from the rear end to the front end of the heat-absorbing material conveying pipe (32) and enters the heat-absorbing material transition chamber (VI). The second step involves heat exchange between the working fluid and liquid oxygen. Gaseous working fluid enters the second cavity (II) from the working fluid transition cavity (VI) and flows from back to front along the second cavity (II); liquid oxygen flows from front to back in the liquid oxygen liquefaction tube (21); the gaseous working fluid outside the liquid oxygen liquefaction tube (21) exchanges heat with the liquid oxygen inside the liquid oxygen liquefaction tube (21), causing the liquid oxygen to be liquefied into gaseous oxygen, and causing the gaseous working fluid to be liquefied into liquid working fluid; The third step involves the reflux of the liquid heat working fluid and the ejection of gaseous oxygen. Under its own gravity, the liquid working fluid flows from the upper part to the lower part of the second chamber (II) and accumulates at the bottom of the container to form hydraulic pressure. The hydraulic pressure drives the liquid working fluid to flow back from front to back to the working fluid transition chamber (VI), and then flows back to the lower part of the working fluid circulation chamber (VII) along the lower working fluid conveying pipe (32). Gaseous oxygen flows from the output end of the liquid oxygen gasification pipe (21) into the gas oxygen delivery pipe (31), and from the gas oxygen delivery pipe (31) into the gas oxygen injection pipe (4), and is ejected outward through the gas oxygen injection hole of the gas oxygen injection pipe (4).

8. The liquid oxygenation method for underground coal gasification according to claim 7, characterized in that, The gaseous working medium in the heat transfer chamber (VI) is divided into two paths: the first path enters the second chamber (II), and the second path enters the third chamber (III). The first heat working medium exchanges heat with the liquid oxygen in the liquid oxygen gasification tube (21) as it flows from back to front along the second cavity (II); The second heat working medium flows from back to front along the third cavity (III), and flows from the front of the third cavity (III) into the front of the second cavity (II), where it exchanges heat with the liquid oxygen in the liquid oxygen gasification pipe (21) at the front of the second cavity (II).

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